The work entailed 40 patients with adult onset asthma divided into two matched groups, 20 patients with acute asthma exacerbation, and 20 patients with chronic stable asthma.
Serum samples from from all studied patients were tested for the presence of C.pneumoniae specific antibodies (IgG,IgM)using enzyme linked immuonosorbent assay.Seropositive samples for IgGwere further examined with microimmunofluorescence(MIF)test for titration of IgG antibodies against c.pneumoniae.An IgG titer of ≥512 was inerperted as evidence of acute primary infection or re-infection,and IgG titer of 64-256 for chronic infection .Nasopharyngeal swab specimens for detection of c.pneumoniae by polymerase chain reaction assay,sputum culture and pulmonary function tests were also performed.
Seropositivity to c.pneumoniae specific IgG was found in 85% and in 80% of patients with acute exacerbation and chronic asthma respectively.In seropositive cases, MIF test illustrated IgG titers consistent with acute infection in 8/17(47.1%)of cases with acute exacerbation versus 3/16(18.8%)with chronic asthma.IgG titers indicating chronic infection were detected in 9/17(52.9%)cases with acute exacerbation compared to 13/16(81.3%)with chronic stable asthma.The mean log titer of IgG was significanly higher in acute asthma than in chronic asthma.IgM could not be detected in any of the studied patients suggesting that acute infection was due to re-infection.PCR detected c.pneumoniae infection in 5 cases with acute exacerbation and had serological evidence of acute infection.All patients with acute infection showed severe airway obstruction.Significant inverse relationship was found between IgGtiterand indices of airway obstuction in both studied groups. Stepwise regression analysis revealed that IgG titer was mainly related to FEF 25-75%.
Re-infection and chronic infection with c.pneumoniae are common in adult onset asthma .C.pneumoniae could be a triggering factor for asthma exacerbation.The high IgG titeres of IgG antibody to C.pneumoniae and its strong relationship with the pulmonary physiological impairment in patients with acute and chronic asthma provide evidence that c.pneumoniae can play role in the immunopathogenesis and severity of asthma presentation.
Effort aiming at evaluating and eradicating infection with c.pneumoniae are recommended for proper asthma control.
Iman Hatata, None.